Merge branch 'main' of https://github.com/bigbodycobain/Shadowbroker into fix/287-rate-limit-proxy-aware

backend/routers/data.py

@@ -98,6 +98,88 @@ def _current_etag(prefix: str = "") -> str:
     return f"{prefix}v{get_data_version()}-l{get_active_layers_version()}"
 
 
+# ── Issue #288: viewport-aware payloads ─────────────────────────────────────
+# Heavy, density-driven, time-sensitive layers that benefit from bbox
+# filtering. Light reference layers (datacenters, military_bases,
+# power_plants, satellites, weather, news, etc.) are intentionally NOT
+# in these sets — they ship world-scale even when bounds are supplied so
+# panning never reveals an "empty world" of static infrastructure.
+#
+# When the caller does NOT pass s/w/n/e, none of this runs and the response
+# is byte-for-byte identical to the pre-#288 behavior.
+_FAST_BBOX_HEAVY_KEYS: tuple[str, ...] = (
+    "commercial_flights",
+    "military_flights",
+    "private_flights",
+    "private_jets",
+    "tracked_flights",
+    "ships",
+    "cctv",
+    "uavs",
+    "liveuamap",
+    "gps_jamming",
+    "sigint",
+    "trains",
+)
+_SLOW_BBOX_HEAVY_KEYS: tuple[str, ...] = (
+    "gdelt",
+    "firms_fires",
+    "kiwisdr",
+    "scanners",
+    "psk_reporter",
+)
+
+
+def _has_full_bbox(s, w, n, e) -> bool:
+    return None not in (s, w, n, e)
+
+
+def _bbox_etag_suffix(s, w, n, e) -> str:
+    """Quantize bbox to 1° before mixing into the ETag.
+
+    The 20% padding inside _bbox_filter already absorbs sub-degree pans;
+    quantizing here means small mouse drags don't blow the ETag cache
+    on the client. Full-world bounds collapse to a single suffix.
+    """
+    if not _has_full_bbox(s, w, n, e):
+        return ""
+    try:
+        ss = math.floor(float(s))
+        ww = math.floor(float(w))
+        nn = math.ceil(float(n))
+        ee = math.ceil(float(e))
+    except (TypeError, ValueError):
+        return ""
+    # If the requested window covers basically the whole world, treat it as
+    # "no bbox" for caching purposes so world-zoomed clients all hit the
+    # same ETag and benefit from the existing 304 path.
+    lat_span, lng_span = _bbox_spans(s, w, n, e)
+    if lng_span >= 300 or lat_span >= 120:
+        return ""
+    return f"|bbox={ss},{ww},{nn},{ee}"
+
+
+def _apply_bbox_to_payload(payload: dict, heavy_keys: tuple[str, ...],
+                            s: float, w: float, n: float, e: float) -> dict:
+    """In-place filter the heavy-key collections in *payload* to a viewport.
+
+    Items without lat/lng are passed through (so e.g. summary blobs aren't
+    accidentally dropped). The existing _bbox_filter helper applies a 20%
+    pad and handles antimeridian crossings.
+    """
+    lat_span, lng_span = _bbox_spans(s, w, n, e)
+    # World-scale request → skip filtering entirely. Spares the CPU and
+    # guarantees the response matches the no-params shape.
+    if lng_span >= 300 or lat_span >= 120:
+        return payload
+    for key in heavy_keys:
+        items = payload.get(key)
+        if not isinstance(items, list) or not items:
+            continue
+        payload[key] = _bbox_filter(items, s, w, n, e)
+    return payload
+
+
 def _json_safe(value):
     if isinstance(value, float):
         return value if math.isfinite(value) else None
@@ -479,13 +561,14 @@ async def bootstrap_critical(request: Request):
 @limiter.limit("120/minute")
 async def live_data_fast(
     request: Request,
-    s: float = Query(None, description="South bound (ignored)", ge=-90, le=90),
-    w: float = Query(None, description="West bound (ignored)", ge=-180, le=180),
-    n: float = Query(None, description="North bound (ignored)", ge=-90, le=90),
-    e: float = Query(None, description="East bound (ignored)", ge=-180, le=180),
+    s: float = Query(None, description="South bound — when all four bounds are supplied, heavy/dense layers (vessels, aircraft, sigint, CCTV, …) are filtered to this viewport with 20% padding. Static reference layers (satellites, etc.) always ship world-scale.", ge=-90, le=90),
+    w: float = Query(None, description="West bound (see s)", ge=-180, le=180),
+    n: float = Query(None, description="North bound (see s)", ge=-90, le=90),
+    e: float = Query(None, description="East bound (see s)", ge=-180, le=180),
     initial: bool = Query(False, description="Return a capped startup payload for first paint"),
 ):
-    etag = _current_etag(prefix="fast|initial|" if initial else "fast|full|")
+    bbox_suffix = _bbox_etag_suffix(s, w, n, e)
+    etag = _current_etag(prefix=("fast|initial|" if initial else "fast|full|") + bbox_suffix.lstrip("|") + ("|" if bbox_suffix else ""))
     if request.headers.get("if-none-match") == etag:
         return Response(status_code=304, headers={"ETag": etag, "Cache-Control": "no-cache"})
     from services.fetchers._store import (active_layers, get_latest_data_subset_refs, get_source_timestamps_snapshot)
@@ -525,6 +608,11 @@ async def live_data_fast(
         payload = _cap_fast_startup_payload(payload)
     else:
         payload = _cap_fast_dashboard_payload(payload)
+    # Issue #288: bbox filter heavy/dense layers only when all four bounds
+    # are supplied. Without bounds, behaviour is byte-for-byte identical
+    # to the pre-#288 implementation.
+    if _has_full_bbox(s, w, n, e):
+        payload = _apply_bbox_to_payload(payload, _FAST_BBOX_HEAVY_KEYS, s, w, n, e)
     return Response(content=orjson.dumps(_sanitize_payload(payload)), media_type="application/json",
         headers={"ETag": etag, "Cache-Control": "no-cache"})
 
@@ -533,12 +621,13 @@ async def live_data_fast(
 @limiter.limit("60/minute")
 async def live_data_slow(
     request: Request,
-    s: float = Query(None, description="South bound (ignored)", ge=-90, le=90),
-    w: float = Query(None, description="West bound (ignored)", ge=-180, le=180),
-    n: float = Query(None, description="North bound (ignored)", ge=-90, le=90),
-    e: float = Query(None, description="East bound (ignored)", ge=-180, le=180),
+    s: float = Query(None, description="South bound — when all four bounds are supplied, heavy/dense layers (gdelt, firms_fires, kiwisdr, scanners, psk_reporter) are filtered to this viewport with 20% padding. Static reference layers (datacenters, military bases, power plants, weather, news, …) always ship world-scale.", ge=-90, le=90),
+    w: float = Query(None, description="West bound (see s)", ge=-180, le=180),
+    n: float = Query(None, description="North bound (see s)", ge=-90, le=90),
+    e: float = Query(None, description="East bound (see s)", ge=-180, le=180),
 ):
-    etag = _current_etag(prefix="slow|full|")
+    bbox_suffix = _bbox_etag_suffix(s, w, n, e)
+    etag = _current_etag(prefix="slow|full|" + bbox_suffix.lstrip("|") + ("|" if bbox_suffix else ""))
     if request.headers.get("if-none-match") == etag:
         return Response(status_code=304, headers={"ETag": etag, "Cache-Control": "no-cache"})
     from services.fetchers._store import (active_layers, get_latest_data_subset_refs, get_source_timestamps_snapshot)
@@ -592,6 +681,12 @@ async def live_data_slow(
         "crowdthreat": (d.get("crowdthreat") or []) if active_layers.get("crowdthreat", True) else [],
         "freshness": freshness,
     }
+    # Issue #288: bbox filter heavy/dense layers only when all four bounds
+    # are supplied. Static reference layers (datacenters, military bases,
+    # power_plants, etc.) deliberately stay world-scale so panning never
+    # hides the infrastructure overlay the operator already has on screen.
+    if _has_full_bbox(s, w, n, e):
+        payload = _apply_bbox_to_payload(payload, _SLOW_BBOX_HEAVY_KEYS, s, w, n, e)
     return Response(
         content=orjson.dumps(_sanitize_payload(payload), default=str, option=orjson.OPT_NON_STR_KEYS),
         media_type="application/json",

backend/tests/test_live_data_viewport_bbox.py

@@ -0,0 +1,273 @@
+"""Tests for issue #288: viewport bbox filtering on /api/live-data/{fast,slow}.
+
+Behaviour contract:
+ * Without s/w/n/e params, the response is byte-for-byte identical to the
+   pre-#288 implementation. (No filtering, no extra fields, no ETag change.)
+ * With s/w/n/e supplied, heavy/dense layers are filtered to that viewport
+   with a 20% padding box.
+ * Light reference layers (datacenters, military_bases, power_plants,
+   satellites, news, weather, …) are NEVER filtered, even when bounds are
+   supplied — panning must never reveal an "empty world" of infrastructure.
+ * World-scale bounds (lng_span >= 300 OR lat_span >= 120) short-circuit
+   filtering and share the global ETag.
+ * The ETag includes a 1°-quantized bbox so two viewports never poison each
+   other's 304 cache.
+"""
+
+import pytest
+
+
+# ───────────────────────── /api/live-data/fast ─────────────────────────────
+
+
+class TestFastBboxFiltering:
+    def _seed_fast(self, monkeypatch):
+        """Plant deterministic heavy + light fixtures across the globe."""
+        from services.fetchers import _store
+
+        # Heavy collections: dense across the world.
+        commercial = [
+            {"lat": -60.0, "lng": -120.0, "id": "f-sw"},   # south Pacific
+            {"lat": 35.0, "lng": -75.0, "id": "f-ne"},     # eastern US
+            {"lat": 35.0, "lng": 100.0, "id": "f-asia"},   # Asia
+        ]
+        ships = [
+            {"lat": -60.0, "lng": -120.0, "id": "s-sw"},
+            {"lat": 35.0, "lng": -75.0, "id": "s-ne"},
+        ]
+        cctv = [{"lat": 35.0, "lng": -75.0, "id": "c-1"}]
+
+        # Sigint heavy collection.
+        sigint = [
+            {"source": "meshtastic", "lat": 35.0, "lng": -75.0, "id": "sig-east"},
+            {"source": "meshtastic", "lat": 35.0, "lng": 100.0, "id": "sig-asia"},
+        ]
+
+        # Light/reference layer — must NEVER be filtered.
+        satellites = [
+            {"lat": -60.0, "lng": -120.0, "id": "sat-sw"},
+            {"lat": 35.0, "lng": -75.0, "id": "sat-ne"},
+            {"lat": 35.0, "lng": 100.0, "id": "sat-asia"},
+        ]
+
+        monkeypatch.setitem(_store.latest_data, "commercial_flights", commercial)
+        monkeypatch.setitem(_store.latest_data, "ships", ships)
+        monkeypatch.setitem(_store.latest_data, "cctv", cctv)
+        monkeypatch.setitem(_store.latest_data, "sigint", sigint)
+        monkeypatch.setitem(_store.latest_data, "satellites", satellites)
+        # Ensure all layers are on so the response includes them.
+        for layer in (
+            "flights", "ships_military", "ships_cargo", "ships_civilian",
+            "ships_passenger", "ships_tracked_yachts", "cctv",
+            "sigint_meshtastic", "sigint_aprs", "satellites",
+        ):
+            monkeypatch.setitem(_store.active_layers, layer, True)
+
+    def test_no_bbox_returns_world_data(self, client, monkeypatch):
+        self._seed_fast(monkeypatch)
+        r = client.get("/api/live-data/fast")
+        assert r.status_code == 200
+        data = r.json()
+        # All heavy fixtures pass through unchanged.
+        assert len(data["commercial_flights"]) == 3
+        assert len(data["ships"]) == 2
+        assert len(data["sigint"]) == 2
+        # Light layer also full.
+        assert len(data["satellites"]) == 3
+
+    def test_bbox_filters_heavy_layers(self, client, monkeypatch):
+        self._seed_fast(monkeypatch)
+        # Box tightly around the eastern-US fixture (lat 35, lng -75).
+        # ±5° → after 20% padding inside _bbox_filter, ~±6° window.
+        r = client.get("/api/live-data/fast?s=30&w=-80&n=40&e=-70")
+        assert r.status_code == 200
+        data = r.json()
+        # Heavy layers: only the eastern-US fixture survives.
+        assert {f["id"] for f in data["commercial_flights"]} == {"f-ne"}
+        assert {s["id"] for s in data["ships"]} == {"s-ne"}
+        assert {c["id"] for c in data["cctv"]} == {"c-1"}
+        assert {s["id"] for s in data["sigint"]} == {"sig-east"}
+
+    def test_bbox_does_not_filter_light_layers(self, client, monkeypatch):
+        self._seed_fast(monkeypatch)
+        r = client.get("/api/live-data/fast?s=30&w=-80&n=40&e=-70")
+        assert r.status_code == 200
+        data = r.json()
+        # Satellites are a reference layer — must NOT be bbox-filtered.
+        assert len(data["satellites"]) == 3
+
+    def test_world_scale_bbox_skips_filtering(self, client, monkeypatch):
+        self._seed_fast(monkeypatch)
+        # lng_span = 360 → treated as world-scale; same as no bbox.
+        r = client.get("/api/live-data/fast?s=-90&w=-180&n=90&e=180")
+        assert r.status_code == 200
+        data = r.json()
+        assert len(data["commercial_flights"]) == 3
+        assert len(data["ships"]) == 2
+
+    def test_partial_bbox_is_treated_as_no_bbox(self, client, monkeypatch):
+        self._seed_fast(monkeypatch)
+        # Only three of four bounds → filtering must NOT engage.
+        r = client.get("/api/live-data/fast?s=30&w=-80&n=40")
+        assert r.status_code == 200
+        data = r.json()
+        assert len(data["commercial_flights"]) == 3
+
+    def test_etag_changes_with_bbox(self, client, monkeypatch):
+        self._seed_fast(monkeypatch)
+        r_world = client.get("/api/live-data/fast")
+        r_local = client.get("/api/live-data/fast?s=30&w=-80&n=40&e=-70")
+        assert r_world.status_code == 200
+        assert r_local.status_code == 200
+        etag_world = r_world.headers.get("etag")
+        etag_local = r_local.headers.get("etag")
+        assert etag_world and etag_local
+        assert etag_world != etag_local, (
+            "ETag must differ between world and regional bbox to prevent "
+            "304 cache poisoning across viewports"
+        )
+
+    def test_etag_stable_for_subdegree_pan(self, client, monkeypatch):
+        self._seed_fast(monkeypatch)
+        # Sub-degree pan should land in the same 1°-quantized bucket.
+        r_a = client.get("/api/live-data/fast?s=30&w=-80&n=40&e=-70")
+        r_b = client.get("/api/live-data/fast?s=30.3&w=-79.8&n=39.7&e=-70.4")
+        assert r_a.headers.get("etag") == r_b.headers.get("etag")
+
+    def test_if_none_match_returns_304_for_same_bbox(self, client, monkeypatch):
+        self._seed_fast(monkeypatch)
+        r1 = client.get("/api/live-data/fast?s=30&w=-80&n=40&e=-70")
+        etag = r1.headers.get("etag")
+        r2 = client.get(
+            "/api/live-data/fast?s=30&w=-80&n=40&e=-70",
+            headers={"If-None-Match": etag},
+        )
+        assert r2.status_code == 304
+
+
+# ───────────────────────── /api/live-data/slow ─────────────────────────────
+
+
+class TestSlowBboxFiltering:
+    def _seed_slow(self, monkeypatch):
+        from services.fetchers import _store
+
+        # Heavy collections.
+        gdelt = [
+            {"lat": 35.0, "lng": -75.0, "id": "g-east"},
+            {"lat": 35.0, "lng": 100.0, "id": "g-asia"},
+        ]
+        firms_fires = [
+            {"lat": 35.0, "lng": -75.0, "id": "fire-east"},
+            {"lat": -10.0, "lng": 120.0, "id": "fire-ido"},
+        ]
+        # Light/reference layers — must always ship in full.
+        datacenters = [
+            {"lat": 35.0, "lng": -75.0, "id": "dc-east"},
+            {"lat": 35.0, "lng": 100.0, "id": "dc-asia"},
+            {"lat": -10.0, "lng": 120.0, "id": "dc-ido"},
+        ]
+        military_bases = [
+            {"lat": 35.0, "lng": -75.0, "id": "mb-east"},
+            {"lat": -10.0, "lng": 120.0, "id": "mb-ido"},
+        ]
+        power_plants = [
+            {"lat": 35.0, "lng": -75.0, "id": "pp-east"},
+            {"lat": 35.0, "lng": 100.0, "id": "pp-asia"},
+        ]
+
+        monkeypatch.setitem(_store.latest_data, "gdelt", gdelt)
+        monkeypatch.setitem(_store.latest_data, "firms_fires", firms_fires)
+        monkeypatch.setitem(_store.latest_data, "datacenters", datacenters)
+        monkeypatch.setitem(_store.latest_data, "military_bases", military_bases)
+        monkeypatch.setitem(_store.latest_data, "power_plants", power_plants)
+        for layer in (
+            "global_incidents", "firms", "datacenters", "military_bases", "power_plants",
+        ):
+            monkeypatch.setitem(_store.active_layers, layer, True)
+
+    def test_no_bbox_returns_world_data(self, client, monkeypatch):
+        self._seed_slow(monkeypatch)
+        r = client.get("/api/live-data/slow")
+        assert r.status_code == 200
+        data = r.json()
+        assert len(data["gdelt"]) == 2
+        assert len(data["firms_fires"]) == 2
+        assert len(data["datacenters"]) == 3
+
+    def test_bbox_filters_heavy_layers(self, client, monkeypatch):
+        self._seed_slow(monkeypatch)
+        r = client.get("/api/live-data/slow?s=30&w=-80&n=40&e=-70")
+        assert r.status_code == 200
+        data = r.json()
+        assert {g["id"] for g in data["gdelt"]} == {"g-east"}
+        assert {f["id"] for f in data["firms_fires"]} == {"fire-east"}
+
+    def test_bbox_leaves_reference_layers_untouched(self, client, monkeypatch):
+        """Datacenters, bases, and power plants are infrastructure overlays —
+        they must remain world-scale so panning never hides them."""
+        self._seed_slow(monkeypatch)
+        r = client.get("/api/live-data/slow?s=30&w=-80&n=40&e=-70")
+        assert r.status_code == 200
+        data = r.json()
+        assert len(data["datacenters"]) == 3
+        assert len(data["military_bases"]) == 2
+        assert len(data["power_plants"]) == 2
+
+    def test_antimeridian_bbox(self, client, monkeypatch):
+        from services.fetchers import _store
+        # Box that straddles the antimeridian (Pacific): w=170, e=-170.
+        gdelt = [
+            {"lat": 0.0, "lng": 175.0, "id": "in-west"},
+            {"lat": 0.0, "lng": -175.0, "id": "in-east"},
+            {"lat": 0.0, "lng": 0.0, "id": "out-mid"},
+        ]
+        monkeypatch.setitem(_store.latest_data, "gdelt", gdelt)
+        monkeypatch.setitem(_store.active_layers, "global_incidents", True)
+        r = client.get("/api/live-data/slow?s=-10&w=170&n=10&e=-170")
+        assert r.status_code == 200
+        data = r.json()
+        ids = {g["id"] for g in data["gdelt"]}
+        assert "in-west" in ids
+        assert "in-east" in ids
+        assert "out-mid" not in ids
+
+
+# ─────────────────── Direct helper coverage (defensive) ─────────────────────
+
+
+class TestHelpers:
+    def test_has_full_bbox(self):
+        from routers.data import _has_full_bbox
+        assert _has_full_bbox(1, 2, 3, 4)
+        assert not _has_full_bbox(None, 2, 3, 4)
+        assert not _has_full_bbox(1, None, 3, 4)
+        assert not _has_full_bbox(1, 2, None, 4)
+        assert not _has_full_bbox(1, 2, 3, None)
+
+    def test_bbox_etag_suffix_quantizes(self):
+        from routers.data import _bbox_etag_suffix
+        a = _bbox_etag_suffix(30.1, -79.6, 39.9, -70.1)
+        b = _bbox_etag_suffix(30.4, -79.2, 39.4, -70.8)
+        assert a == b, "Sub-degree pan must collapse to the same ETag suffix"
+        assert a.startswith("|bbox=")
+
+    def test_bbox_etag_suffix_world_collapses(self):
+        from routers.data import _bbox_etag_suffix
+        # World-scale → empty suffix (shares the global ETag).
+        assert _bbox_etag_suffix(-90, -180, 90, 180) == ""
+
+    def test_bbox_etag_suffix_partial_is_empty(self):
+        from routers.data import _bbox_etag_suffix
+        assert _bbox_etag_suffix(None, -180, 90, 180) == ""
+
+    def test_apply_bbox_preserves_non_list_values(self):
+        from routers.data import _apply_bbox_to_payload, _FAST_BBOX_HEAVY_KEYS
+        payload = {
+            "commercial_flights": [{"lat": 35, "lng": -75, "id": "x"}],
+            "satellite_source": "tle",  # not a list, must pass through
+            "sigint_totals": {"total": 1},  # dict — must pass through
+        }
+        out = _apply_bbox_to_payload(dict(payload), _FAST_BBOX_HEAVY_KEYS, 30, -80, 40, -70)
+        assert out["satellite_source"] == "tle"
+        assert out["sigint_totals"] == {"total": 1}

frontend/src/components/map/hooks/useViewportBounds.ts

@@ -8,6 +8,7 @@ import {
   normalizeViewBounds,
   type ViewBounds,
 } from '@/lib/viewportPrivacy';
+import { setLiveDataBounds } from '@/lib/liveDataViewport';
 
 const VIEWPORT_POST_DEBOUNCE_MS = 2500;
 const VIEWPORT_POST_MIN_INTERVAL_MS = 12000;
@@ -70,6 +71,17 @@ export function useViewportBounds(
       window.dispatchEvent(new CustomEvent(VIEWPORT_COMMITTED_EVENT));
     }
 
+    // Issue #288: hand the same coarsened/expanded bounds to the live-data
+    // poller so heavy collections in /api/live-data/{fast,slow} can be
+    // scoped to the visible region. Static reference layers are unaffected
+    // — see backend _FAST_BBOX_HEAVY_KEYS / _SLOW_BBOX_HEAVY_KEYS.
+    setLiveDataBounds({
+      south: preloadBounds.south,
+      west: preloadBounds.west,
+      north: preloadBounds.north,
+      east: preloadBounds.east,
+    });
+
     // Debounce POSTing viewport bounds to backend for dynamic AIS stream filtering
     if (debounceTimerRef.current) clearTimeout(debounceTimerRef.current);
     debounceTimerRef.current = setTimeout(() => {

frontend/src/hooks/useDataPolling.ts

@@ -1,6 +1,7 @@
 import { useEffect, useRef } from "react";
 import { API_BASE } from "@/lib/api";
 import { mergeData, setBackendStatus as setStoreBackendStatus } from "./useDataStore";
+import { appendLiveDataBoundsParams } from "@/lib/liveDataViewport";
 
 export type BackendStatus = 'connecting' | 'connected' | 'disconnected';
 
@@ -32,8 +33,8 @@ export async function forceRefreshLiveData(): Promise<void> {
 
   try {
     const [fastRes, slowRes] = await Promise.all([
-      fetch(`${API_BASE}/api/live-data/fast`),
-      fetch(`${API_BASE}/api/live-data/slow`),
+      fetch(appendLiveDataBoundsParams(`${API_BASE}/api/live-data/fast`)),
+      fetch(appendLiveDataBoundsParams(`${API_BASE}/api/live-data/slow`)),
     ]);
 
     if (fastRes.ok) {
@@ -85,9 +86,13 @@ export const LAYER_TOGGLE_EVENT = 'sb:layer-toggle';
 /**
  * Polls the backend for fast and slow data tiers.
  *
- * All data is fetched globally (no bbox filtering) — the backend returns its
- * full in-memory cache and MapLibre culls off-screen entities on the GPU.
- * This eliminates the "empty map when zooming out" lag.
+ * Issue #288: heavy, density-driven layers (vessels, aircraft, gdelt
+ * events, fires, sigint, …) are bbox-scoped to the visible map area via
+ * `appendLiveDataBoundsParams`. Static reference layers (datacenters,
+ * military bases, power plants, satellites, weather, news, …) are NOT
+ * filtered backend-side, so panning never reveals an "empty world" of
+ * infrastructure. World-zoomed views skip bbox params entirely and hit
+ * the shared ETag cache exactly like the pre-#288 behaviour.
  *
  * The AIS stream viewport POST (/api/viewport) is still handled separately
  * by useViewportBounds to limit upstream AIS ingestion.
@@ -147,7 +152,9 @@ export function useDataPolling() {
         const useStartupPayload = !fetchedStartupFastPayload && !fastEtag.current;
         const headers: Record<string, string> = {};
         if (!useStartupPayload && fastEtag.current) headers['If-None-Match'] = fastEtag.current;
-        const url = `${API_BASE}/api/live-data/fast${useStartupPayload ? '?initial=1' : ''}`;
+        const url = appendLiveDataBoundsParams(
+          `${API_BASE}/api/live-data/fast${useStartupPayload ? '?initial=1' : ''}`,
+        );
         const res = await fetch(url, {
           headers,
           signal: controller.signal,
@@ -193,10 +200,13 @@ export function useDataPolling() {
       try {
         const headers: Record<string, string> = {};
         if (slowEtag.current) headers['If-None-Match'] = slowEtag.current;
-        const res = await fetch(`${API_BASE}/api/live-data/slow`, {
-          headers,
-          signal: controller.signal,
-        });
+        const res = await fetch(
+          appendLiveDataBoundsParams(`${API_BASE}/api/live-data/slow`),
+          {
+            headers,
+            signal: controller.signal,
+          },
+        );
         if (res.status === 304) { scheduleNext('slow'); return; }
         if (res.ok) {
           slowEtag.current = res.headers.get('etag') || null;

frontend/src/lib/liveDataViewport.ts

@@ -0,0 +1,84 @@
+/**
+ * Shared module-level state for the current map viewport bounds, used by
+ * `useDataPolling` to scope `/api/live-data/{fast,slow}` to the visible
+ * area when the user has zoomed in.
+ *
+ * Issue #288: the backend now bbox-filters dense layers (vessels, aircraft,
+ * gdelt events, fires, sigint, …) when all four bounds are supplied. Light
+ * reference layers stay world-scale. Heavy collections aren't sent over the
+ * wire for parts of the planet the operator isn't looking at, which cuts
+ * the steady-state poll from ~27 MB to ~5 MB for a typical regional view.
+ *
+ * No bounds set → callers omit the params entirely → backend ships full
+ * world data (byte-identical to pre-#288 behaviour). This keeps the cold
+ * boot path (where no map is mounted yet) and the world-zoomed view
+ * unchanged.
+ */
+
+export interface LiveDataBounds {
+  south: number;
+  west: number;
+  north: number;
+  east: number;
+}
+
+let _current: LiveDataBounds | null = null;
+
+/** True when lng_span ≥ 300 OR lat_span ≥ 120. Backend treats these as
+ *  world-scale and skips filtering — so the frontend doesn't bother sending
+ *  bounds at all, which keeps the ETag cache shared across operators in the
+ *  zoomed-out case. */
+function isEffectivelyWorld(bounds: LiveDataBounds): boolean {
+  const latSpan = Math.max(0, bounds.north - bounds.south);
+  let lngSpan = bounds.east - bounds.west;
+  if (lngSpan < 0) lngSpan += 360;
+  return lngSpan >= 300 || latSpan >= 120;
+}
+
+/** Push the latest committed bounds. Called from `useViewportBounds`
+ *  whenever the map's bounds change enough to matter. Pass `null` to
+ *  fall back to world-scale fetching (e.g. on unmount). */
+export function setLiveDataBounds(bounds: LiveDataBounds | null): void {
+  if (bounds === null) {
+    _current = null;
+    return;
+  }
+  if (
+    !Number.isFinite(bounds.south) ||
+    !Number.isFinite(bounds.west) ||
+    !Number.isFinite(bounds.north) ||
+    !Number.isFinite(bounds.east)
+  ) {
+    _current = null;
+    return;
+  }
+  if (isEffectivelyWorld(bounds)) {
+    // World-zoomed → fetch globally, share the ETag cache across operators.
+    _current = null;
+    return;
+  }
+  _current = bounds;
+}
+
+/** Read the current bounds, or `null` if the caller should fetch the full
+ *  world payload. Reader contract: must tolerate `null` and call without
+ *  bbox params in that case. */
+export function getLiveDataBounds(): LiveDataBounds | null {
+  return _current;
+}
+
+/** Append `s/w/n/e` query params to a URL when bounds are set, otherwise
+ *  return the URL unchanged. Centralised so all live-data callers stay in
+ *  sync about quantization and the world-scale skip rule. */
+export function appendLiveDataBoundsParams(url: string): string {
+  const b = _current;
+  if (!b) return url;
+  const sep = url.includes('?') ? '&' : '?';
+  // Match backend ETag quantization (1° floor/ceil) so the client and
+  // server agree on which bounds round to the same cache key.
+  const s = Math.floor(b.south);
+  const w = Math.floor(b.west);
+  const n = Math.ceil(b.north);
+  const e = Math.ceil(b.east);
+  return `${url}${sep}s=${s}&w=${w}&n=${n}&e=${e}`;
+}